Vaulted building structure

ABSTRACT

The vaulted building structure comprises a shell (1) made of a composite construction material and formed of arcuate elements (4) of a uniform width having their ends (5) mounted on a base (3). The shell (1) is shaped as a cylindrical vault of which the vertical axis of symmetry includes a vault ridge (2). The ends (5) of the arcuate elements (4) are hingedly braced to the base (3) for rotation about a horizontal axis parallel with the vertical plane of symmetry. The convex outer surface of each arcuate element (4) has its curvature gradually diminishing lengthwise of the arcuate element (4) towards its ends (5) and ridge (2) for levelling out strains generated in the shell (1) upon rotation of the ends (5) of the arcuate elements (4).

BACKGROUND OF THE INVENTION

The invention relates to construction and to building structures, andmore particularly it relates to a vaulted building structure.

FIELD OF THE INVENTION

It is generally known that the cost of construction of vaulted buildingstructures is significantly lower than of framed structures; thus, theinput of concrete is lower by 25-30% and of steel by up to 25%, and thetotal cost is lower by 12 to 14%. On the other hand, the input of steelinto ferroconcrete structures is 4 to 5 times less than into buildingswith all-metal structures.

The construction of monolithic or solid cast-in-situ building structuresrequires extended construction facilities and is economically feasibleonly in industrially developed areas.

Contractors have accumulated considerable experience in erecting theshells of vaulted buildings and structures, such as the domes andceilings of production shops, pavilions, grain storages, hangars, minorsports halls and auditoriums made of individual components, e.g. withthe use of panel shells.

The use of panel shells in construction yields considerable savings whenvaulted building structures are erected.

In general, the industrial manufacture and use of panel shells inconstruction have been found to yield sizeable economy and to save theinput of both materials and labour.

However, a vaulted building structure made of panel shells requires aload-bearing skeleton or cage, in most cases made of metal, and itsconstruction involves the sealing of joints and application ofwaterproofing coatings.

The thickness of the shell of a vaulted building structure is determinedfrom calculations accounting for the total load applied to the shell,the strength ratings of the construction material used and of the metalreinforcement. The common practice is to arrange the metal reinforcementcloser to either the outer or inner surface of the shell, and to apply aprotecting coating 10-15 mm thick to safeguard the reinforcement againstcorrosion.

Due to relatively large dimensions vaulted building structures are inmost cases constructed on supports. The general practice is to makeindividual panel shells at manufacturing works and then to ship them tothe construction site where diverse handling equipment is operated toassemble them into a vaulted building structure. Consequently, thedesign of the panel shells has to provide for shipment and handlingloads, which generally results in an increased input of materials intothe structures. The same problems are encountered when shells areconstructed without a load-bearing cage.

As it has been already mentioned, the use of structures made of panelshells is not economically feasible in areas remote from theconstruction industry centres, on account of the problems encountered inerecting such structures, concerning both the shipment cost and thecomplexity of the assembly work requiring specific handling equipment.These extra costs can be as high as 50 to 200% of the cost of thestructure itself.

The load-bearing capacity of thin-wall shells is dependent on theirstrength, rigidity and stability, and, consequently, the service life ofvaulted structures is dependent on the geometric shape and dimensions ofsuch shells.

High load-bearing capacity is offered by thin-wall shells of vaultedbuilding structures of the cylindrical type, made of jointed arcuateelements with a convex outer surface having their ends bearing upon abase. The central angle of such arcuate elements is generally from 130°to 150° , the width of the arcuate element being uniform throughout itslength. The actual geometric dimensions of arcuate elements, i.e. theirwidth and the curvature radius of the outer surface are dependent on thedimensions (the length and height) of the vaulted structures, defined bytheir intended use.

There is known a vaulted building structure comprising a shell of acomposite construction material, formed by arcuate elements of a uniformwidth with a convex outer surface, having their ends bearing upon thebase, the structure being shaped as a cylindrical vault of which thevertical plane of symmetry includes the ridge of the vault. The outerconvex surface of each arcuate element has a uniform curvature, and,hence, the rigidity of the shell is also uniform throughout its length.Each arcuate element is made of two indentical parts hingedly joined atthe ridge. The ends of the arcuate elements are made fast with the base.

In constructing this vaulted building structure, the shell is assembledfrom individual arcuate elements, and their joints are sealed, whichinvolves a considerable input of labour into the construction, and alsoa large input of the composite construction material, to say nothing ofthe necessity of having specific equipment for performing the jobs ofsealing the joints and the shell. The presence of a hinge at the ridgeinvolves extra constraints in the structure. The stability of astructure of this kind against external action is not high. Thus, in theplaces where the ends of the arcuate elements are secured, the action ofexternal loads generates a great bending moment which could lead to astrained state of the shell capable of causing its breakdown, one of themain external actions ultimately causing a breakdown of the shell beingits surface heating.

The above described design of a vaulted building structure rendersimpossible making its shell solid, e.g. cast in situ, as theload-bearing capacity of such a shell is inadequate, and the setting ofa composite construction material applied on a formwork shaped as theshell-to-be results in exceedingly high shrinkage strain which is atleast 5 times greater than the strain under the action of externalloads.

SUMMARY OF THE INVENTION

The present invention aims at providing a vaulted building structure,having such a connection between the ends of arcuate elements and abase, and such an outer surface of the arcuate elements as to ensure anincreased load-bearing capacity of its shell with simultaneous reductionof the cost of its construction.

With this aim in view, the present invention resides in a vaultedbuilding structure having its shell made of a composite constructionmaterial and formed of arcuate elements of a uniform width with a convexouter surface, having their ends mounted on a base, the shell beingshaped as a cylindrical vault of which the vertical plane of symmetryincludes the ridge of the vault; the ends of the arcuate elements beinghingedly braced to the base for rotation about a horizontal axisparallel with the vertical plane of symmetry; the outer surface of eacharcuate element having its curvature gradually diminishing lengthwise ofthe arcuate element towards its ends and the ridge for levelling out thestrain generated in the shell during rotation of the ends of the arcuateelements.

It is expedient that in the vaulted building structure the arcuateelements should be substantially arrow-shaped, retaining this shape uponrotation of the end of the arcuate elements.

It is further reasonable that in the vaulted building structure theshell should have its thickness gradually increasing lengthwise of eacharcuate element from the ridge towards the respective ends of thearcuate element.

The hinged bracing of the shell with the base ensures that when theshell is strained under the action of the loads exerted thereupon, theends of the arcuate elements are capable of rotation about thehorizontal axis of the hinge parallel with the vertical plane ofsymmetry of the shell, the bending moment generated by the action ofexternal loads at the hinge substantially equalling zero.

As it has been already mentioned, when the ends of arcuate elements arerigidly secured, the bending moment generated at the cross-section ofthe arcuate element at the base is 5 times as great as the bendingmoment generated at the most threatened cross-section of the arcuateelement of the disclosed vaulted building structure. Thus, theintroduction of the support hinges levels out the bending moment alongthe neutral line of the arcuate element, enhancing the load-bearingcapacity of the structure. The smooth variation of the curvature of theconvex outer surface of the arcuate element reduces, respectively, therigidity of the shell at sections situated at the ridge and at the endsof the arcuate elements, with the strain caused by external forcesgrowing, and the temperature-induced strain lowering. The total strainin the shell would lower, stepping up the safety factor of the shell,and hence, the load-bearing capacity of the arcuate building structureas a whole. The enhanced safety factor of the structure allows to makethe shell of the disclosed vaulted building structure solid, e.g. castin situ with the aid of shotcreating and pneumatic formwork. With thecurvature of the ends of the arcuate elements being relatively small,the hinged bracing of the ends of the arcuate elements with the base isrelatively easily attained.

As it has been mentioned, when a shell is made by being cast in situ,the setting of the composite construction material generates a shrinkagestrain which is substantially greater than the strain caused by theaction of external forces and the weight of the structure, the strainbeing at its utmost at the sections adjoining the ridge of the shell.The arrow-like shape of the arcuate element in combination with theminimized thickness of the shell at the sections adjoining the ridgeenhances still further the strength of the solid shell and theload-bearing capacity of the vaulted building structure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further described in connection with itspreferred embodiments, with reference being made to the accompanyingdrawings, wherein:

FIG. 1 is a general side view of a vaulted building structure embodyingthe invention;

FIG. 2 shows on a larger scale a sectional view taken on line II--II ofFIG. 1;

FIG. 3 shows in more detail a sectional view taken on line III--III ofFIG. 2;

FIG. 4 shows in more detail a sectional view taken on line IV--IV ofFIG. 2;

FIG. 5 shows in more detail a sectional view taken on line V--V of FIG.2;

FIG. 6 shows the same, as FIG. 2, for the version of the shell witharrow-shaped arcuate elements, in accordance with the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

In the drawings, the proposed vaulted building structure comprises ashell 1 (FIG. 1) of a composite construction material which can be aconstruction material based on a cement binder reinforced with glassfibre resistant to the cement medium, with fillers, such as sand,cinders and other additives.

The shell 1 is shaped as a cylindrical vault with the vertical axis ofsymmetry including the ridge 2 of the vault. The shell 1 is mounted on abase 3 and is formed of jointed arcuate elements 4 having their ends 5braced with the base 3.

Depending on the soil characteristics and the intended use of thestructure, the base 3 can be either a strip foundation with piles or acast-in-situ ferro-concrete rectangular platform. The width "b" of thearcuate elements 4 is uniform throughout their length, its actual sizedepending on the strength characteristics of the composite constructionmaterial used, the length "M" of the vaulted building structure and itsspan. In practice, the width "b" of the arcuate element 4 can be from 1m to 5 m. The number of the arcuate elements 4 in the structure is alsodependent on the length "M" of the vaulted building structure and thewidth "b" of a single arcuate element 4, and it may be various. In theembodiment illustrated in FIG. 1 the number of the arcuate buildingelements 4 is eight.

The central angle of the arcuate elements 4 is selected from a range of150° to 180° . The ends 5 (FIG. 2) of the arcuate elements 4 areassociated with cylindrical bearing hinges 6 providing for rotation ofthe ends 5 of the arcuate elements 4 about a horizontal axis parallelwith the vertical plane of symmetry of the vault.

The arcuate elements 4 have a convex outer surface shaped as a body ofrevolution. Thus, in the embodiment being described the outer surface ofthe arcuate elements 4 is toroidal. The curvature of the outer surfaceof each arcuate element 4 gradually varies lengthwise of each element 4for levelling out the strain generated in the shell 1 as the ends 5 ofthe arcuate elements rotate under the load. It is generally known thatloads acting upon the shell 1 of a vaulted building structure are theeffects of winds and snow, its own weight, temperature-induced andshrinkage strain --both during the setting of the composite constructionmaterial of the shell 1 and during the service life of the vaultedbuilding structure. The curvature "K" of the outer surface of eacharcuate element 4 is at its maximum at the section of the arcuateelement 4 along the portion covering from 1/3 to 1/3 of the length "L"of the arcuate element 4 between the end 5 and the ridge 2 thereof (i.e.along the portion representing the middle third of the length "L" of oneside of the arcuate element 4), gradually diminishing towards the ends 5and ridge 2 of the arcuate element 4. In FIG. 3, H_(max) is the rise ofthe arc of the circle in section of the arcuate element 4 where itsouter surface has the maximum curvature K_(max) =1/R_(min), whereR_(min) is the radius of the outer surface of the arcuate element 4. InFIG. 4, H₁ is the rise of the arc of the circle in cross-section of thearcuate element 4 at the ridge 2 of the vault; in FIG. 5, H₂ is the riseof the arc of the circle in cross-section at the end 5 of the arcuateelement 4.

The values of H_(max), H₁ and H₂ are determined from computationsaccounting for the dimensions of the vaulted building structure, thestrength characteristics of the composite construction material, theexternal action, and should satisfy the following conditions:

    0≦H.sub.1 ≦2/5H.sub.max ; 1/5H.sub.max ≦H.sub.2 ≦3/4H.sub.max.

In the embodiment illustrated in FIG. 6, the arcuate elements 7 of thevaulted building structure have an arrow-like shape retainable uponrotation of their hingedly braced ends 8, which enhances the stability,rigidity and, hence, the load-bearing capacity of the shell 1. Theminimum thickness h_(min) of the shell 1 is determined from computationsfor a given composite construction material and required dimensions ofthe shell 1 in a known procedure, depending on the external action, theintended use of the structure and climatic conditions.

In the embodiment illustrated in FIG. 2, the arcuate elements 4 have athickness "h" gradually increasing lengthwise of each arcuate element 4from the ridge 2 towards the ends 5 of the arcuate element 4.

In the disclosed vaulted building structure the action of external loadsmakes the ends 5 (FIGS. 1 and 2) of the arcuate elements 4 turn in theircylindrical bearing hinges 6 (FIG. 2), so that the shell 1 becomessomewhat deformed with the maximum bending moments being generated atsections at the ridge 2 of the shell 1 and at sections spaced from theends 5 of the arcuate elements 4 by about 1/7 L. With the rigidity ofthe shell 1, owing to the varying curvature "K" of its outer surfacelengthwise of the arcuate element 4, diminishing towards the ridge 2 andends 5, the strain produced in the shell 1 is levelled out.

In construction of the shell 1 of the vaulted building structure bycasting in situ, the setting of the composite construction materialgenerates shrinkage strain in the shell 1, while oppositely directedhorizontally extending reaction forces are generated at the cylindricalbearing hinges 6. With the ends of the arcuate elements 4 beingdisplaced correspondingly, each arcuate element 4 is somewhat bent, andits each section is somewhat turned. Had the curvature of the outersurface of the shell 1 been uniform, the maximum bending moment causedby the shrinkage strain would have been located in the area of the ridge2. Since in the disclosed structure the curvature of the outer surfaceof the arcuate element 4 gradually diminishes towards the ridge 2, and,consequently, the height of the cross-section of the arcuate element 4gradually diminishes towards the ridge 2, the shrinkage strain in theshell 1 is reduced. In other words, with the shell 1 being less rigidand the deformation being of the same magnitude as in the structures ofthe prior art, the reaction forces at the cylindrical bearing hinges 6are reduced, and the strain at sections of the arcuate element 4 islikewise reduced. In this way the levelling out of the strain lengthwiseof each arcuate element 4 takes place.

In case of temperature-induced strain, the latter generates an effort ofthrust at the cylindrical bearing hinges 6, i.e. the reaction forcesgenerated there are opposite to those produced by the shrinkage strain.It should be pointed out that when the shrinkage strain equals thetemperature-induced strain, the two strains completely eliminate eachother.

In the arrow-shaped vaulted building structure illustrated in FIG. 6, azone is defined in the vicinity of the ridge 2 which takes up in thebest possible way the rotation of the ends 8 of the arcuate components7, its performance resembling that of a "resilient" hinge, i.e. a hingewhere a bending moment is set, proportional to the rotation of the ends8 of the arcuate elements 7 relative to the ridge 2. In this case thereduction and levelling out of the strain in the shell 1 is optimal.

For the present invention to be better understood, given below are someillustations of its practical implementation.

EXAMPLE 1

The vaulted building structure is 12 m wide, 6 m high, 24 m long, and isintended as a garage for automotive vehicles. It is constructed bycasting in situ with the use of a pneumatic formwork by shotcreting amortar of a composite construction material. The composite constructionmaterial--glass--fibre/cement concrete--is produced of a cement mortarreinforced with glass fibre resistant to the cement medium, the averageglass fibre length being 40 mm. The percentage of glass fibre in theglass-fibre/cement concrete is 3%. The sand-cement ratio in the mortaris 0.5:1. The water-solid (cement+sand) ratio is 0.4:1. The shell 1(FIG. 2) is made of eight arcuate elements 4, 2 cm thick and 3 m wide.The rise H₁ of the arc of the circle of the arcuate element 4 at thesection at the ridge 2 is 300 mm, and the rise H₂ of the arc of thecircle at the section at the end 5 of the arcuate element 4 is 100 mm.The rise H_(max) of the arc of the circle at the section of the arcuateelement 4, having the maximum curvature, is 600 mm and is spaced fromthe ends 5 of the arcuate elements 4 by 0.53 L. The strengthcomputations have accounted for the environmental and service conditionsof the structure. The shrinkage of the material is 0.002. Thecomputations have shown that the maximum strain is located at thesection of the ridge 2 and at a section spaced by 1/8 1 from the end 5of the arcuate element 4. The total strain σ at the section of the ridge2 in the area of the maximum value of its rise is about 42 kg/cm². Inthe area of the joints of the arcuate elements 4 the total strain σ is-80 kg/cm².

The total strain at the section of the arcuate element 4 spaced by 1/8 Lfrom the end 5 of the end thereof is, as follows: in the area of themaximum value of the rise σ=-9 kg/cm², and in the area of the joints ofthe arcuate elements 4, σ=46 kg/cm².

It should be mentioned that with the above proportions of the geometricdimensions of the vaulted building structure and with the givenconstruction material, the temperature-induced strain opposes theshrinkage strain and compensates for it. The computations have indicatedthat the shell 1 would retain its load-bearing capacity when beingheated from 1° C. to 40° C.

EXAMPLE 2

The vaulted building structure intended for use as a grain storage hasthe dimensions of Example 1, with the exception of the thickness of theshell 1 gradually increasing from the ridge 2 toward the ends 5 of thearcuate elements 4 from 25 mm to 40 mm, whereby the strain at the mostendangered sections is 10-15% less than in Example 1.

EXAMPLE 3

The vaulted building structure has the dimensions of the Example 1, withthe exception of the arcuate elements 7 (FIG. 6) being arrow-shaped, theheight of the span being 6.75 m. With this configuration, the strainproduced in the shell 1 by winds would grow, the snow load woulddiminish, the load of the own weight would remain the same. The strainat the section of the ridge 2 caused by shrinkage is 5-8% lower than inthe structure of the Example 1. Thus, the arrow-like shape of the shellenhances the load-bearing capacity of the vaulted building structure ofthe present invention.

INDUSTRIAL APPLICABILITY

The disclosed vaulted building structure can be used in buildings andstructures of different kinds, such as grain storages, warehouses,garages, hangars, minor sports halls and auditoriums made of compositeconstruction materials.

We claim:
 1. A vaulted building structure having its shell (1) made of acomposite construction material and formed of arcuate elements (4) of auniform width having a convex outer surface, having their ends (5)mounted on a base, the shell being shaped as a cylindrical vault ofwhich the vertical plane of symmetry includes the ridge (2) of thevault, characterized in that the ends (5) of the acruate elements (4)are hingedly braced to the base (9) for rotation about a horizontal axisparallel with the vertical plane of symmetry, the outer surface of eacharcuate element (4) having its curvature gradually diminishinglengthwise of the arcuate element (4) toward the ends (5) and the ridge(2) thereby levelling out strains generated in the shell (1) in rotationof the ends (5) of the arcuate elements (4).
 2. A vaulted buildingstructure as claimed in claim 1, characterized in that the arcuateelements (7) are of an arrow-like shape retainable upon rotation of theends (8) of the arcuate elements (7).
 3. A vaulted building structure asclaimed in claim 1, characterized in that the shell (1) has itsthickness gradually increasing lengthwise of each arcuate element (4)from the ridge (2) towards the ends (5) of the arcuate element (4).